Aquatell

Illinois

The 49 hardness figures we’ve verified run from 1.3 to 28 grains per gallon, with a median of 11; 86% are hard or very hard.

How the 49 figures spread across the bands

  • Soft 0
  • Slightly hard 1
  • Moderately hard 6
  • Hard 14
  • Very hard 28
Hardness
11 gpg medianAverage 12 gpg (209 ppm), from 1.3 to 28. Each published figure counts once in the average, median and spread; a figure published as a range is shown as its range and isn't averaged.
Coverage
49 places49 listings as published
Disinfectant
1 of 5use chloramine; 4 use chlorine

Every place we have

Sources are each city’s water quality report or its utility. Gather the listings up by place or by the water system that serves them, or see every listing as published; open a group to see what’s in it.

49 places

On the scaleDisinfectantSourcesAsk Aqua
St. Charles
Published as a range
  • Published as a range, 187 to 476 ppm (11 to 28 gpg): shown as a range and left out of averages.
 11–28 gpg187–476 ppm, very hard – Hardness
Peoria
No source linked
  • The page it came from links no primary source for this figure.
 26 gpg450 ppm, very hard –
Carol Stream
No source linked
  • The page it came from links no primary source for this figure.
 24 gpg418 ppm, very hard –
Romeoville
No source linked
  • The page it came from links no primary source for this figure.
 24 gpg395 ppm, very hard –
Joliet
No source linked
  • The page it came from links no primary source for this figure.
 23 gpg388 ppm, very hard Chlorine Disinfectant
Elmhurst
No source linked
  • The page it came from links no primary source for this figure.
 21 gpg362 ppm, very hard –
Des Plaines
2 notes
  • Published as 350 ppm and 18 gpg, which don't agree: 350 ppm is 20.5 gpg. The ppm figure is used (water reports give mg/L).
  • The page it came from links no primary source for this figure.
 21 gpg350 ppm, very hard –
Lombard
No source linked
  • The page it came from links no primary source for this figure.
 20 gpg344 ppm, very hard –
Wayne
No source linked
  • The page it came from links no primary source for this figure.
 20 gpg334 ppm, very hard –
Orland Park
No source linked
  • The page it came from links no primary source for this figure.
 19 gpg322 ppm, very hard –
Downers Grove
No source linked
  • The page it came from links no primary source for this figure.
 17 gpg288 ppm, very hard –
Naperville
No source linked
  • The page it came from links no primary source for this figure.
 17 gpg288 ppm, very hard Chlorine Disinfectant
Plainfield
No source linked
  • The page it came from links no primary source for this figure.
 16 gpg280 ppm, very hard –
East Peoria
No source linked
  • The page it came from links no primary source for this figure.
 15 gpg250 ppm, very hard –
Granite City
No source linked
  • The page it came from links no primary source for this figure.
 15 gpg250 ppm, very hard –
Palatine
No source linked
  • The page it came from links no primary source for this figure.
 14 gpg245 ppm, very hard –
Elmwood Park
No source linked
  • The page it came from links no primary source for this figure.
 13 gpg218 ppm, very hard –
Oak Lawn
No source linked
  • The page it came from links no primary source for this figure.
 13 gpg222 ppm, very hard –
East Saint Louis
No source linked
  • The page it came from links no primary source for this figure.
 12 gpg210 ppm, very hard –
Melrose Park
No source linked
  • The page it came from links no primary source for this figure.
 12 gpg222 ppm, very hard –
Moline
No source linked
  • The page it came from links no primary source for this figure.
 12 gpg210 ppm, very hard –
Oak Park
No source linked
  • The page it came from links no primary source for this figure.
 12 gpg212 ppm, very hard –
Thornton
No source linked
  • The page it came from links no primary source for this figure.
 12 gpg196 ppm, very hard –
Cicero
No source linked
  • The page it came from links no primary source for this figure.
 11 gpg187 ppm, very hard –
Danville
No source linked
  • The page it came from links no primary source for this figure.
 11 gpg191 ppm, very hard –
Decatur
No source linked
  • The page it came from links no primary source for this figure.
 11 gpg194 ppm, very hard –
Dekalb
No source linked
  • The page it came from links no primary source for this figure.
 11 gpg188 ppm, very hard –
Kankakee
No source linked
  • The page it came from links no primary source for this figure.
 11 gpg196 ppm, very hard –
Glenview
No source linked
  • The page it came from links no primary source for this figure.
 8.8 gpg150 ppm, hard –
New Trier
No source linked
  • The page it came from links no primary source for this figure.
 8.8 gpg150 ppm, hard –
Chicagoland
No source linked
  • The page it came from links no primary source for this figure.
 8.7 gpg148 ppm, hard –
Glen Ellyn
No source linked
  • The page it came from links no primary source for this figure.
 8.7 gpg148 ppm, hard –
Waukegan
No source linked
  • The page it came from links no primary source for this figure.
 8.2 gpg140 ppm, hard –
Chicago
No source linked
  • The page it came from links no primary source for this figure.
 8.0 gpg148 ppm, hard Chlorine Disinfectant
Crystal Lake
No source linked
  • The page it came from links no primary source for this figure.
 8.0 gpg137 ppm, hard –
Arlington Heights
No source linked
  • The page it came from links no primary source for this figure.
 7.9 gpg134 ppm, hard –
Evanston
No source linked
  • The page it came from links no primary source for this figure.
 7.9 gpg134 ppm, hard –
Skokie
No source linked
  • The page it came from links no primary source for this figure.
 7.9 gpg134 ppm, hard –
Wheeling
No source linked
  • The page it came from links no primary source for this figure.
 7.9 gpg134 ppm, hard –
Aurora
No source linked
  • The page it came from links no primary source for this figure.
 7.7 gpg130 ppm, hard Chloramine Disinfectant
Elgin
No source linked
  • The page it came from links no primary source for this figure.
 7.5 gpg128 ppm, hard –
Columbus
No source linked
  • The page it came from links no primary source for this figure.
 7.0 gpg120 ppm, hard –
Capital
No source linked
  • The page it came from links no primary source for this figure.
 6.8 gpg115 ppm, moderately hard –
Springfield
No source linked
  • The page it came from links no primary source for this figure.
 6.8 gpg115 ppm, moderately hard –
Mount Prospect
No source linked
  • The page it came from links no primary source for this figure.
 6.5 gpg110 ppm, moderately hard –
Bolingbrook
No source linked
  • The page it came from links no primary source for this figure.
 6.4 gpg108 ppm, moderately hard –
Lake Forest
No source linked
  • The page it came from links no primary source for this figure.
 5.9 gpg100 ppm, moderately hard –
Champaign
No source linked
  • The page it came from links no primary source for this figure.
 5.3 gpg90 ppm, moderately hard –
Rockford
No source linked
  • The page it came from links no primary source for this figure.
 1.3 gpg22 ppm, slightly hard Chlorine Disinfectant

Missing your city? Aquatell researches cities on request from the utility’s own reports, usually within a week. A note on a figure says what we found when we checked it: units that didn’t agree, another page with a different figure, a range.

What to do about it

Hard water

Above about 3.5 grains per gallon, scale builds in water heaters, fixtures and appliances. A softener sized for your hardness and household removes it for the whole house.

Water softenersSizing a softener

Chlorine or chloramine

Standard carbon removes chlorine’s taste and smell. Chloramine lasts longer in the pipes and needs catalytic carbon to remove it.

Carbon and chloramine filters

Not sure what you need?

Aqua knows these figures and Aquatell’s treatment charts, and can size a system for your home.

Softeners for Illinois’s water

See them all